Netstar *******

I have purchased a Netstar Tracker for my vehicle in August 2020 and the agreed amount is R169 monthly.However Netstar Tracker deducted R234 at times R299 from my account. I tried calling the customer service but I kept holding until my airtime ran out. I wrote email and there was no response. Please Netstar Tracker let's stick to the agreement or R169 per month or please cancel my contract.